We use our own domain to send with smtp.somedomainname.com as an example, via port 587. The error is "Failed to send opt-in email, please contact us and inform about this error."
The problem is with the subscription widget.

Just deactivated all plugins except e-newsletter. When I try to subscribe it gives a screen error "Failed to send opt-in email, please contact us and inform about this error.". I do receive the subscription email though

I don't believe I've seen this before... It could be due to the mail server's configuration!
If the email gets to you without any issues, I would simply ignore the error message as clearly it's a simple case of the mailserver not sending the proper response, even though it accepts the data from the plugin.

i have a problem, i need a help,
I just bought the plugin, and does not work, and tried everything, I've seen the forums, look for solutions and not working, I need help, or tell me to do to get my money back.

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